1. Technical Field of the Invention
The present invention relates generally to an electric rotating machine with a cooling mechanism which is designed to ensure cooling ability in supplying coolant to coil ends of a stator of the electric rotating machine even when the electric rotating machine is tilted in any direction.
2. Background Art
Japanese Patent No. 4167886 teaches a cooling mechanism for cooling coil ends of a stator installed in an electric rotating machine. The cooling mechanism includes arc-shaped coolant channels to which a liquid coolant is fed. Each of the coolant channels has openings formed in a bottom thereof as coolant outlets from which the coolant is drained onto a corresponding one of the coil ends. The coolant channel also has hollow cylindrical guides joined to the outlets, respectively, to guide streams of the coolant into selected portions of the coil end in order to ensure the capability of the cooling mechanism in cooling the coil end.
The electric rotating machine is usually tilted for some reason in either of opposite horizontal directions in which an rotating axis of the electric rotating machine is inclined. In order to ensure the cooling capability in such an event, the coolant outlets are arranged in two lines, with the outlets being staggered between the two lines in a lengthwise direction of the coolant channel. When the electric rotating machine is tilted in either of the horizontal directions, the coolant is drained at least from either of the two-line coolant outlets, thereby assuring the draining of the coolant onto the coil end.
The electric rotating machine may, however, be tilted in another direction in which the axis is merely turned without being inclined. The cooling mechanism is so designed that the coolant is supplied to the central top of the arc-shaped coolant channel. When the electric rotating machine is tilted in the above axis-turning direction, it may, therefore, result in a failure in draining the coolant from either of opposed ends of the coolant channel onto a portion of the coil end.
The coolant outlets of the coolant channel are located just above an outer circumferential surface of the coil end. The coolant drops from the cylindrical guides and flows downward along the outer circumferential surface of the coil end and, thus, hardly reaches an outer or an inner surfaces of the coil end which are opposed in the axial direction of the coil end, which may result in a lack in cooling the coil end as a whole.
The above cooling mechanism, therefore, has the problem in that the cooling capability may be deteriorated depending upon a direction in which the electric rotating machine is tilted.